1. Field of the Invention
The present invention relates to the field of nutraceuticals and to the use of dietary supplements to maintain or improve ocular health.
2. Description of the Related Art
Dietary supplements are recommended for a variety of reasons including the improvement of vision or prophylaxis of vision loss. An example of dietary supplements useful in improving ocular nutrition and promoting healthy eyes are the ICaps® Dietary Supplements (Alcon Laboratories, Inc., Fort Worth, Tex.). Dietary supplements are generally consumed in the form of powders, tablets, capsules or gel-caps and comprise a variety of vitamins, minerals, and herbal or other organic constituents. Some dietary supplements are formulated with beadlets, which may function as carriers for the nutritional ingredients and may be blended and compressed into tablets or filled into capsules or gel caps.
Zinc, an essential nutrient, is the second most abundant trace element in the human body and the most abundant trace element in the eye. It is necessary for the activity of more than 200 enzymes and for the DNA binding capacity of over 400 nuclear regulatory elements. There is evidence that zinc may function as an antioxidant by protecting sulfhydryl groups from oxidation, competing with copper and iron to reduce the formation of hydroxyl radicals which are a result of redox cycling and by the induction of the antioxidant protein metallothionein (MT) which can scavenge damaging hydroxyls.
It has been suggested that oxidative stress and a decrease in anitoxidant capacity play a role in several pathological conditions such as atherosclerosis, carcinogenesis, and macular degeneration. Age-related macular degeneration (AMD) is the number one cause of blindness in people over 60 in the United States. It is thought that it is an age-related defect in the retinal pigment epithelium (RPE) which contributes to this disease, however, the etiology is unknown and currently there is no cure.
Zinc is an important micronutrient that plays an essential role in human growth and function. Zinc is necessary for the activity of over a hundred enzymes, including carbonic anhydrase, superoxide dismutase and alkaline phosphatase. Zinc acts as a cofactor for numerous metalloenzymes, including retinol dehydrogenase and catalase. Zinc also is a cofactor in the synthesis of extracellular matrix molecules, is essential for cell membrane stability, is needed for normal immune function, is associated with melanin and is taken up in a facilitated manner by the retinal pigment epithelium.
U.S. Pat. No. 6,586,611 describes a molecular structure for a zinc monocysteine complex. The '611 patent provides only one structure for the zinc monocysteine complex described and does not describe other zinc complexes. What is needed is a more bioavailable form of zinc, in a form other than the zinc monocysteine complex previously described, in order for it to be more effective for use in dietary supplements for the improvement of ocular health.